Differences between physical and chemical change are essential background knowledge that the students must possess. The students can already distinguish between ionic and molecular compounds, using the periodic table to determine the charge of an ion. They can also apply the rules for naming and writing formulas for ionic and molecular compounds. Students are familiar with the seven elements that exist as diatomic molecules. In this lesson, students will learn how to express a chemical reaction in word and formula equations using their knowledge of formula compounds. They will also learn how to apply the law of conservation of mass to chemical equations. This is an important skill in Chemistry because chemists use chemical equations to describe the microscopic happenings of a reaction. Students will apply these skills by creating macroscopic models of the microscopic world of chemical reactions using gum drops and toothpicks. Knowing how to write and balance equations will help students to identify types of reactions and formation of precipitates.
Objectives
Students will… Distinguish between physical and chemical changes of matter Describe chemical reactions using symbols and correct chemical formulas
Apply the law of conservation of mass in balancing chemical equations
Write balanced chemical equations when given the names or formulas of the reactants and products in a chemical reaction.
Construct models of chemical reactions using gum drops and toothpicks
Propose his/her own chemical reaction as a word equation
-Rotten and fresh apples
-Textbook for additional examples
-Toothpicks
-Gum drops
-Homework worksheet copies(attached below)
-Adopt-a-Chem Rxn worksheet copies(attached below)
Instruction
Opening (15 minutes)
Do-Now: Answer the questions on the board in your notebook. Open your textbook to pg. 203 and start reading Sec. 8.1. (We will go over the answers to the questions as a class)
1) Write the correct chemical formula for the following compound/molecule: barium sulfate, carbon dioxide, copper(II) chloride
2) What are the differences between physical vs. chemical changes? Give examples of each.
If students have trouble writing correct chemical formulas, spend a few minutes reviewing. If students have trouble differentiating between physical and chemical changes, show a rotten and ripe apple. Cutting the apple is physical while rotting is chemical because the apple will taste different and new compounds are formed.
Explain that today's focus is on chemical changes and by the end, they should be able to write equations that describe chemical reactions and be able to balance such equations. There will be a quiz at the end of lecture on balancing equations!
Middle (60 minutes)
Activity 1: 30 mins
Interactive Discussion: Students will first watch Hindenburg video clip. I will ask the students how we can explain what happened in the video? Do we know what elements/compounds caused such a massive explosion? Can we write the reaction in the form of a word equation? Because we know there is hydrogen and oxygen present, and these are both diatomic molecules, can we write the reaction in the form of a formula equation?
What are other examples of chemical reactions that we encounter in our lives (burning gasoline, rusting iron, ripening fruit, tarnishing silver, baking bread, photosynthesis)?
What must we combine to burn gasoline (hydrocarbons and oxygen)? Therefore, all products must be created from the pieces that they are made up of. All these reactions to form new things have certain characteristics. We can describe these reactions using chemical equations, as we did with the Hindenburg example. But what must be conserved (charge and matter)?
Going back to the Hindenburg clip, are matter and charge conserved? NO! So, we must figure out a way to conserve! Let's figure out a way to balance this and any other chemical equation. Would it be useful to introduce the (unbalanced) version of this reaction and then walk students through figuring out how to write it as balanced?
As a class, the students will be walked through writing and balancing the reaction of Sodium hydroxide with hydrogen chloride to form water and sodium chloride. I will have a student come up and right the correct chemical formula for each compound in the reaction. Next we will balance the reaction of calcium with oxygen to form calcium oxide. While going step by step through this problem, I will write the generic steps for each part and have students write this in their notebook. How will you do this so that it allows the appropriate level of struggle? Can you do this so that students can give YOU the rules of the process after two or three examples? Can you start this process with the equation for combustion of hydrogen in order to have a smooth transition from video?
Write the correct chemical formula for each compound in the chemical equation *REMEMBER DIATOMIC MOLECULES*
Draw a line through the reaction arrow
List the elements present on each side of the equation and how many atoms of each element is present
Start balancing one element at a time until every element has an equal number of atoms on both sides *ONLY PLACE NUMBERS IN FRONT OF THE COMPOUND*
Make sure all coefficients are in the lowest possible ratio
Activity 2: 30 mins
Students will work in groups of 4 (they can choose groups) at the lab benches. I will give each group a word equation written on a sheet of paper, gum drops, and toothpicks. The students will have to write correct chemical formulas for each compound in the reaction, create a model of each compound using the gum drops and toothpicks, then balance the equation by putting coefficients in front of the compounds they have created. I will walk around and monitor each group's progress in balancing the equation given. If any groups finish quickly, I will give them more reactions to balance, and if they finish those, they will create their own word equation that another group must turn into a balanced chemical equation. So students will arrange the gum drops to represent an equation? Are you concerned that they might "learn" that the reactants and the products consists of different atoms?
Explain to students that eating, throwing, putting gum drops in their mouths is strictly prohibited. If they do not follow instructions, we will not do the activity. Good point!
Some examples of reactions to use:
Iron reacts with oxygen to form iron(III) oxide
carbon with oxygen to form carbon dioxide
magnesium with chlorine to form magnesium chloride
aluminum combines with oxygen to form aluminum oxide
hydrogen reacts with sulfur to form hydrogen sulfide
silver nitrate combines with hydrogen sulfide to form silver sulfide and nitric acid (HNO3)
iron(III) chloride reacts with sodium hydroxide to form iron(III) hydroxide and sodium chloride
Good examples. Will students represent these reactions in their notes somewhere?
Closing (15 minutes)
Regroup: I will put some chemical equations on the board. Have students solve independently, then I will ask to see their answers. Students will hold up their answers and I will use this as an informal assessment.
2PbO2 -> 2PbO + O2
4H2 + Fe3O4 -> 3Fe + 4H2O
Quiz: Balance the following chemical reaction and hand it in- sodium chloride reacts with sulfuric acid (H2SO4) to produce sodium sulfate and hydrochloric acid (HCl)
2NaCl + H2SO4 -> Na2SO4 + 2HCl
Hand out Adopt-A-Chemical Reaction Project sheet & discuss the requirements
Pass out homework: Writing and Balancing Chemical Equations Worksheet
Balanced equation for Hindenburg example: 2H2(g) + O2(g) --> 2H2O(l) + Energy Nice.
Ethylene gas is released once fruit is picked and causes ripening to occur..eventually leads to rotting So bacteria are not involved?
Lesson #1: Describing Chemical Change
Summary
Differences between physical and chemical change are essential background knowledge that the students must possess. The students can already distinguish between ionic and molecular compounds, using the periodic table to determine the charge of an ion. They can also apply the rules for naming and writing formulas for ionic and molecular compounds. Students are familiar with the seven elements that exist as diatomic molecules. In this lesson, students will learn how to express a chemical reaction in word and formula equations using their knowledge of formula compounds. They will also learn how to apply the law of conservation of mass to chemical equations. This is an important skill in Chemistry because chemists use chemical equations to describe the microscopic happenings of a reaction. Students will apply these skills by creating macroscopic models of the microscopic world of chemical reactions using gum drops and toothpicks. Knowing how to write and balance equations will help students to identify types of reactions and formation of precipitates.Objectives
Students will…Distinguish between physical and chemical changes of matter
Describe chemical reactions using symbols and correct chemical formulas
Apply the law of conservation of mass in balancing chemical equations
Write balanced chemical equations when given the names or formulas of the reactants and products in a chemical reaction.
Construct models of chemical reactions using gum drops and toothpicks
Propose his/her own chemical reaction as a word equation
Materials
-PPT with Do-Now and Hindenburg video clip-Rotten and fresh apples
-Textbook for additional examples
-Toothpicks
-Gum drops
-Homework worksheet copies(attached below)
-Adopt-a-Chem Rxn worksheet copies(attached below)
Instruction
Opening (15 minutes)
Middle (60 minutes)
Activity 1: 30 mins- As a class, the students will be walked through writing and balancing the reaction of Sodium hydroxide with hydrogen chloride to form water and sodium chloride. I will have a student come up and right the correct chemical formula for each compound in the reaction. Next we will balance the reaction of calcium with oxygen to form calcium oxide. While going step by step through this problem, I will write the generic steps for each part and have students write this in their notebook. How will you do this so that it allows the appropriate level of struggle? Can you do this so that students can give YOU the rules of the process after two or three examples? Can you start this process with the equation for combustion of hydrogen in order to have a smooth transition from video?
- Write the correct chemical formula for each compound in the chemical equation *REMEMBER DIATOMIC MOLECULES*
- Draw a line through the reaction arrow
- List the elements present on each side of the equation and how many atoms of each element is present
- Start balancing one element at a time until every element has an equal number of atoms on both sides *ONLY PLACE NUMBERS IN FRONT OF THE COMPOUND*
- Make sure all coefficients are in the lowest possible ratio
Activity 2: 30 mins- Students will work in groups of 4 (they can choose groups) at the lab benches. I will give each group a word equation written on a sheet of paper, gum drops, and toothpicks. The students will have to write correct chemical formulas for each compound in the reaction, create a model of each compound using the gum drops and toothpicks, then balance the equation by putting coefficients in front of the compounds they have created. I will walk around and monitor each group's progress in balancing the equation given. If any groups finish quickly, I will give them more reactions to balance, and if they finish those, they will create their own word equation that another group must turn into a balanced chemical equation. So students will arrange the gum drops to represent an equation? Are you concerned that they might "learn" that the reactants and the products consists of different atoms?
- Explain to students that eating, throwing, putting gum drops in their mouths is strictly prohibited. If they do not follow instructions, we will not do the activity. Good point!
- Some examples of reactions to use:
- Iron reacts with oxygen to form iron(III) oxide
- carbon with oxygen to form carbon dioxide
- magnesium with chlorine to form magnesium chloride
- aluminum combines with oxygen to form aluminum oxide
- hydrogen reacts with sulfur to form hydrogen sulfide
- silver nitrate combines with hydrogen sulfide to form silver sulfide and nitric acid (HNO3)
- iron(III) chloride reacts with sodium hydroxide to form iron(III) hydroxide and sodium chloride
Good examples. Will students represent these reactions in their notes somewhere?Closing (15 minutes)
Notes
Balanced equation for Hindenburg example: 2H2(g) + O2(g) --> 2H2O(l) + Energy Nice.Ethylene gas is released once fruit is picked and causes ripening to occur..eventually leads to rotting So bacteria are not involved?
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